The invention is based on a fuel injection pump as defined hereinafter.
Extraordinarily high pressures arise in the pump work chamber, on the order of 1300 bar and higher, and major demands in terms of injection quality are made of the injection pumps. This is true both for controlling the supply quantity of the fuel to be injected and for controlling the onset of supply. The quality of this control process depends in particular on the operating capacity of the control slide and on the relief bore cooperating with it. The control itself may be effected for instance via one or more oblique grooves disposed in a pump piston, which cooperate with the diversion bore in the control slide.
The cooperation of the control slide with the pump piston depends on the axial length of the control slide and on its rotational position with respect to the pump piston. However, injection pumps are also known in which because of various devices the control slide can move only axially on the pump piston, while the pump piston itself executes not only its reciprocating motion but also a rotation effected by a suitable adjusting device. In each case, the cooperation of the control slide and pump piston defines the onset of high-pressure injection, the injection stroke, and thus the duration of injection. Accordingly, the working capacity of the control depends on the length of the control stroke and on the angle of rotation of the pump piston or control slide. The axial displacement, for instance, of the control slide on the pump piston is determined primarily by the manner in which the control slide and a control rod are coupled.
In a known fuel injection pump (U.S. Pat. No. 2,147,390), the control slide in a variant embodiment moves on the pump piston by the cooperation of a gear wheel segment and a rack; the unavoidable play in a gear wheel drive does not allow accurate control courses.
In another known fuel injection pump of this type (European Patent 0 181 402), a ball-shaped adjusting tang of an adjusting mechanism disposed in the control rod engages the inside of a transverse groove of the control slide so that the adjusting mechanism causes the axial motion of the control slide on the pump piston.
A fuel injection pump of this type is also known (German Offenlegungsschrift 36 30 647), in which a ball-shaped adjusting tang secured to the control rod engages the inside of a transverse groove disposed in the control slide and adjusts it axially.
Another known fuel injection pump of this type (DE 36 33 899 Al) U.S. Pat. No. 4,811,716 also has a transverse groove in the control slide, which groove is engaged by a ball-shaped protrusion of the driver element, which is secured and adjustable on a control rod, and this protrusion then actuates the control slide.
Last but not least, a fuel injection pump of this type is known (from European Application 0 262 167) in which an anti-skid means, seated on an eccentric shaft of an adjusting bolt and engaging a transverse groove of the control slide, axially displaces the control slide.
All these known fuel injection pumps have a major disadvantage that the actuating elements o the control rod must engage transverse grooves of the control slide in order to axially displace it o the pump piston. The control slide must be structurally longer, however, which increases the total height of the pump and makes the pump more expensive. Moreover, the transverse grooves in the control slide weaken its cross section, which in turn can cause damage such as fissuring, given that reciprocating slide injection pumps are developed for very high injection pressures, with peak pressures of about 1000 bar.